MASTER GARDENER: Answers on Cassia trees and bud mites on lemons

Q. I’ve been noticing some flowering trees in a shopping center parking lot that are really nice. They have large clusters of yellow flowers that remind me of giant buttercups. The trees are not very big, although I think they are mature trees. Can you identify them from my description? I think I’d like to plant one if it’s not too difficult to grow.

A. I believe the trees you saw were Cassia trees, either Cassia excelsa, commonly called the Crown of Gold tree, or Cassia leptophylla, commonly called the Gold Medallion tree. Both species of trees produce large clusters of bright yellow flowers in summer. Both have compound leaves with leaflets arranged in pairs along the leaf midrib. C. excelsa has 10 to 20 pairs of leaflets whereas C. leptophylla has 12 or fewer pairs of leaflets. As you have observed, the trees are relatively small in size, with both species typically growing quickly but staying under 25 feet tall at maturity. They usually begin blooming in July and continue through the summer months.

Any time you find plants growing in commercial landscapes, you can be pretty well assured that the plants are trouble-free and tolerant of most growing conditions. Cassias are no exception; they are easy to grow and require only ordinary garden care. The only aspect of their culture that is somewhat unconventional is that they should be pruned in late summer, after they have bloomed, not in the winter, when most plants are pruned. Both species I have mentioned are considered somewhat evergreen, so they always have a presence in the garden.

By examining the number of pairs of leaflets on the trees at the shopping center, you will be able to identify which species of Cassia they are. There are many species of Cassia, but the Gold Medallion tree, C. leptophylla, is probably the most popular species, with the Crown of Gold tree, C. excelsa, being the second most popular. Both are excellent trees for the home landscape and will give you wonderful summer color.

Q. Some of my lemons have multiple points, almost like fingers, at the end of the fruit. Are they mutations?

A. Lemons develop multiple points when they are infested with bud mites. These very tiny sucking insects feed on tender young growth and can cause distorted leaves and fruits. Although they may look peculiar, the lemons usually are still usable. Water stress and dust on the trees can promote increased bud mite populations, so keeping your tree adequately irrigated and free of dust will discourage these damaging insects. Since you can’t count on natural enemies of the bud mite to be in your environment, these simple cultural practices are especially important.

Contact the writer: Ottillia "Toots" Bier has been a UC Cooperative Extension master gardener since 1980. Send comments and questions to features@pe.com.

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